1. Field of the Invention
This invention relates to a mechanically-operated drum brake device provided with a floating type actuator.
2. Description of the Prior Art
There is conventionally used a mechanically-operated drum brake device of the type having a so-called floating type actuator adapted for expanding and actuating a pair of brake shoes, the actuator being usually held at a position floating from the surface of a back plate other than at the time of braking in such a manner as to be suspended between end portions of webs of both the brake shoes in order to prevent the actuator from sticking to the back plate or operating defectively due to rust caused by incoming water or other foreign matter. However, since such floating type actuator is mounted in a floating state, when a brake wire for rotating a brake lever journaled in the actuator is pulled in a direction deviating from the normal turning path of the brake lever due to a position whereat the equipment is disposed or other reason, the brake lever and the actuator are turned slantingly at the time of braking operation, which may be a reason for causing an inproper braking operation.
Further, in case this type of floating actuator is driven by a reaction force caused from turning movement of the brake lever journaled rotatably on the actuator, since a turning shaft for the brake lever as provided on the actuator is positioned closer to the back plate than the engaging position of a working part of the brake lever with the brake shoes and also the engaging position of the actuator with the shoes, that is, near a position whereat the brake lever and the brake wire are coupled to each other, the reaction force caused by turning of the brake lever works so as to float that side of the actuator which engages a brake shoe, thus tends to force the brake shoe to float, which may result in an inconvenient braking operation.